The cost of P & M is high, but as compared to what? When you compare the cost of P to M, since P is 25 times stronger than M you will use much less than M in the formula. The rational for this is the discussion point of P vs. M is, Catylist Vs. Salt., Scale Vs. Contrast and speed or type of processing.

Murray Kelly wrote:Ornello, the issue boils down to the statement the M is NOT regenerated by HQ. This flies in the face of statements to the contrary I have run down in the e-net. As a manufacturer Lowell should know and I want to clear the point up.
For me, P is expensive and HQ is not. Maybe a POTA with added HQ would allow me to use less, cheaper, HQ to boost P in the brew? Its action in MQ developers at low pH is a curiosity I would like to clarify.

According to everything I have read, including Jacobsen and Jacobsen, HQ regenerates both metol and phenidone.

Lowell Huff wrote:The cost of P & M is high, but as compared to what? When you compare the cost of P to M, since P is 25 times stronger than M you will use much less than M in the formula. The rational for this is the discussion point of P vs. M is, Catylist Vs. Salt., Scale Vs. Contrast and speed or type of processing.

There are good formulas being developed all the time that use P and M together and separately with HQ. What's the issue?

It is probably more profitable for manufacturers to make PQ formulae than MQ and they also very robust for specific applications.
Although PQ developers are very versatile and capable of excellent results, I am not convinced that it can entirely supplant Metol formulae for everything.
Metol is used in some types of special purpose developers where extra fine-grain or high acutance is required such as Microdol, Perceptol, Beutlers and FX-1.

Keith Tapscott. wrote:It is probably more profitable for manufacturers to make PQ formulae than MQ and they also very robust for specific applications.
Although PQ developers are very versatile and capable of excellent results, I am not convinced that it can entirely supplant Metol formulae for everything.
Metol is used in some types of special purpose developers where extra fine-grain or high acutance is required such as Microdol, Perceptol, Beutlers and FX-1.

From what I understand, metol is more easily suppressed by development by-products and thus 'gives' a little more in the highlights. With some films that have no softening of gradient as the shoulder is approached, metol may help to reduce that. With such films phenidone may not be as good to tame the highlights.

Kieth: Profitability is determined by the difference in the cost of manufacturing and the demand of the market. Not the cost difference between M & P. For example; when the Doctor's waiting room is full and he has no more time to see any more patients he will raise his price. His cost of doing business did not increase but the market demand did. The reason modern formulas use is P rather than M is that P is a better superadditive than M from all considerations. Why do you think M formulas dilute 1+1 and P formulas dilute 1+4 to 1+19 and provide the same quality image? If you were to use a M formula for the same developing times as a P formula at !+9, the M formula would greatly over develop the image. If still, you are not "convinced" the superiority P formulas, don't listen to me, become a scientist, use the scientific method and convince yourself.

Lowell Huff wrote:Kieth: Profitability is determined by the difference in the cost of manufacturing and the demand of the market. Not the cost difference between M & P. For example; when the Doctor's waiting room is full and he has no more time to see any more patients he will raise his price. His cost of doing business did not increase but the market demand did. The reason modern formulas use is P rather than M is that P is a better superadditive than M from all considerations. Why do you think M formulas dilute 1+1 and P formulas dilute 1+4 to 1+19 and provide the same quality image? If you were to use a M formula for the same developing times as a P formula at !+9, the M formula would greatly over develop the image. If still, you are not "convinced" the superiority P formulas, don't listen to me, become a scientist, use the scientific method and convince yourself.

I agree that phenidone has numerous advantages but metol has some as well. I actually think the PMQ may be best of all. It is not the case that there is no reason to use metol. In fine-grain 35mm work, diluting metol developers allows compensating development, something that phenidone developers don't do very well.

I saw this formula on a web site which is claimed to behave identically to Ilford Microphen, although I can not verify that. I did not see a formula for a replenisher though.
Pentax-Pete who post here sometimes might know.

I have not seen the formula in the original post in any publication or website before, and I first saw it in a post by Pentax-Pete on another forum which was claimed to be Ilford Microphen.
I was curious what the replenisher formula might be if it can be confirmed as Microphen.

That's a really curious conglomeration of pH adjusters.
The Borax/boric acid pair seem to be the dominant pH adjusters, but the addition of the tripolyphosphate and sulphite/bisulphite confuse the issue, somewhat. I can see the need for sulphite (HQ) but otherwise it appears to be a pretty ordinary PQ developer.
Trying to understand its formula.
Murray.

Murray, I read some where that the metabisulphite is used as a preservative in part 'A' of the Ilford P.Q. developers sold in powder form.
I don't think it is used in part 'A' of ID-11 or Perceptol, because Metol is already slightly acidic.

The metabisulphite probably isn't required if the borax and boric-acid is balanced to obtain the desired pH.
I don't actually want to make it from the basic components, I was just curious about this particular formula which appears to be a P.Q. variant of the D-76 type. (Ilford Microphen?)

There are a number of other variants of this formulae which was first published in 1954 with simpler buffering, essentially it's Ilford's PQ version of ID-11/D76, which became known as the Axford-Kedall Fine Grain film developer and was designed for large scale photofinishing use where it's stability was vastly superior to Metol based ID-11/D76 as a PQ developer is more tolerant of Bromide build up so needs less bleed replenishment.

The Axford-Kendal FGF developer after extensive large scale trials was sold as Autophen. The developer was available as a liquid and also in powder form, with 2 different replenishers.

As Keith says Pentaxpete's formula is for a powdered PQ developer, probabbly the powder form of Autophen which the inclusion of Metabisulphite seems to indicate, it's not Microphen which has a different PQ ratio, ph, replenisher etc and was a new developer formulated & released some time after Autophen to further exploit the speed enhancing effects of Phenidone .

Just as Kodak experimented with D76, a,b, c, d , h etc in the 1930's changing the buffering, Ilford did the same with the PQ variant of ID-11/D76 before it's final commercial release.